Electric discharge apparatus



Dec. 3; 1940. L R LUDWlG 2,223,523

ELECTRIC DISCHARGE APPARATUS Filed Nov. 16, 1958 Load 25 DC 5 I app 9 2!L aaa WITNESSES: I INVENTOR Leo/2 R Ludwjy.

517% ATTORN Patented Dec. 3, 1940 STATES ELECTRIC nrsoirsaca z'Pennsylvania Application November 16, 1938, Serial No. 240,703

16 Claims.

My invention relates to electric discharge apparatus and it hasparticular relation to control apparatusfor an electric dischargedevice.

Heretofore, electric discharge devices of the 5 type having an arc-likedischarge have gener-- ally been utilized -only in alternating currentcircuits because of the discontinuous characteristic of the controlelectrode.

It is accordingly an object of my invention to 10 provide a method andapparatus for controlling the transmission of a direct current throughan electric discharge device.

Another object of my invention is to provide apparatus for alternatelystarting and stopping the flow of direct current through an electricdischarge device.

A more specific object of my invention is to provide apparatus forsupplying a. current impulse of short duration for initiating the flowof.

direct current through an electric discharge device'and for thereafterstopping the flow of direct current through the discharge device atwill.

In accordance with my invention unidirectional potential is normallyimpressed between the prin- 25 cipalv electrode of an electric dischargedevice which preferably is of the mercury-pool type but may be of thegrid-controlled gaseous hotcathode type. A charge storingmeans isdisposed to be connected between the starting. or

an ignition electrode and one of the principal electrodes to initiate adischarge between the principal electrodes. Once the discharge has beeninitiated between the principal electrode the a starting electrode is nolonger effective because of the discontinuous characteristic of thedischarge device.

To stop the fiow of current between the principal electrodes the chargestoring means is disconnected f'rom the starting electrodefand connectedbetween the principal electrodes of the electric discharge device. Thecurrent is directed to the charge storing means and the are between theprincipal electrodes-is extinguished.

The novel features that I consider characteristic of my invention areset forth with particularity in the appended claims- The inventionitself, however, both as to its organization and its method ofoperation, together with additional 50 objects-and advantages thereof,will best be understood from the following description of specificembodiments when read in connection with the accompanying drawing, inwhich:

Figure 1 is a diagrammatic view showing an '88 embodiment of myinvention; and,

Fig. 2 is a diagrammatic view showing a modification of my invention.

The apparatus shown in Fig. 1 comprises an electric discharge device iihaving an anode l3, and a cathode l of mercury or any other vaporizingcathode material disposed in a chamber ll of glass or other suitablematerial and that is preferably highly evacuated. If it'should bedesired that the chamber ll be of metal, a. barrier should be insertedto prevent the cathode spot from reaching the chamber wall. A startingor ignition electrode is of suitable resistance material is immersed inthe cathode 85. While in the usual practice of my invention thedischarge device It is of the mercury-cathode type, it may obviously bereplaced by a gaseous electric discharge device of the hot-cathode type.

The electric discharge device it is supplied 4 with potential from asuitable direct current power source (not shown) through a pair of busbars or conductors 2i and 23. The anode i3 is connected to conductor 25and thecathode I5 is connected to conductor 23 through a load 25 of anygeneral character such as a motor orlight source that might be energizedthrough the electric discharge device.

A capacitor 21 of any other suitable charge storingmeans is connectedbetween the cathode 15 of discharge device ii and moving contact member29 of multi-contact switching device 3|. Switching device it may be ofany conventional type as this specific structure forms no'part of thepresent invention. Upper stationary contact member 63 of switchingdevice $5 is connected to anode i3. Lower stationary contact member 35is connected to the ignition electrode l9.

It will readily be understood that the capacitor 21 and the switch 38may be replaced by means in which a first capacitor which is in acharged condition is'connected by a switching means between the ignitionelectrode !9 and the cathode I5 to initiate the flow of current throughthe discharge device I I, and a. second capacitor, which is in anuncharged condition, is connected by a. second switching means betweenthe anode l3 and the cathode l5 to interrupt the flow of current throughthe discharge device II.

To start operation of my system direct current power is applied toconductors 2| and 23 in such manner that positive potential is appliedto anode it, while negative potential is applied through load 2! tocathode i5. If the switching device 8| is in the position shown in Fig.1 the capacitor}! will be charged through a circult which extends fromthe energized conduc- I tor 2|. stationary contact member 33, moving themoving contact member 29 of switching device 3| is actuated so as toopen the v circuit through contact member 33 and close a circuit throughcontact member 35. The capacitor 21 then discharegs through an ignitionelectrode 19 through a circuit which extends from one side ofcapacitorf21, contact members 29 and 35 of switch 3|, ignition electrodel9, cathode 15 to the other side of capacitor 21. A cathode spot isformed on' the surface of the cathode l5 thereby causing a dischargebetween the anode l3 and cathode I5 thus energizing the load 25 througha circuit which extends from energized conductor 2|, anode I3, cathodel5, load 25, conductor 31 to the energized conductor 23.

Once initiated, the discharge between the an l3 and cathode 15. Thecurrent passing through the discharge device is diverted through thecircuit hereinabove described for charging the capacitor and the arcbetween the anode I3 and cathode I5 is extinguished. When the capacitorbecomes charged flow of current between anode l3 and the cathode I5 isnot reestablished because the circuit through the ignitioncelectrode isopen and there is no cathode spot on the surface of the cathode toreinitiate the arc.

The capacitor 21 is now charged and the energization of the dischargedevice H may be repeated as hereinabove described.

The size of capacitor 21 must be great enough. and the impedance of theleads connecting it to the anode and cathode of discharge device Ii besmall enough, so that the transient current capacitor 21 draws whencontact member 29 re,-

turns to contact with contact member 33 is substantially greater thanthe current flowing through discharge device ll before contact member 29makes said contact. This relationship can be insured by making capacitor21 large and by making its connection leads short and of low resistance.

In a system of the type shown in Fig. 1 that I have found particularlyuseful, the electric discharge device II is of the type known asWestinghouse KU-637 and has an average anode to cathode current ratingof 20 amperes. A maximum peak current of approximately 25 amperes isrequiredin the circuit of the ignition electrode l9. When the load 25 issuch that the load current is 12 amperes, thecapacity of capacitor 21may be substantially 4 microfarads. The potential impressed between theprincipal electrodes of the discharge device II is of the order of 250volts. The leads to the capacitor 21 may be of number 10 gage B & Scopper wire preferably. made as short and direct as possible. Forinstance, I have made installations in which the total length of wire inthe path from the anode to the cathode of the discharge device Itthrough the capacitor 21 was approximately 2 feet;

. It is assumed that the time constant of the circuit in Fig. 1 issu'fiicient to allow for the deionization of the discharge device llwhile the capacitor 21 is charging. However. if the distributiveinductance inherent in the load and load circuit is not suflicient forobtaining the proper time constant, an inductance 39 may be addedpreferably in the circuit for charging the capacitor 21 as shown in Fig.2.

In Fig. 2, an electromagnetic device ll having contact members 43, 45and 41 and operating coil 49 is utilized in place of switching device3|. A'spring 5| may be utilized to insure positive closing of contactmembers 43 when the operating coil 49 of the electromagnetic device 4|is in the deenergized condition. A start push-button switch 53 isdepressed to energized operating coil 49 and thus causes the dischargedevice H to become energized. A stop push-button switch 55 is depressedto deenergized operating coil 49 and thus causes the discharge device Hto become d'eenergi zed. 'The operation of the system shown in Fig. 2 issubstantially the same as that shown inFig. 1, therefore it is believedthat a detailed explanation of the operationis not necessary.

It will readily be understood that the electric discharge device ll maybe utilized as a source of light in which case the load 25 may bereplaced by a resistor or reactor if so desired. By moving the contactmember 29 into'contactwith contact member 35 for only brief times, thetube H may be made to exert a series of flashes and be used as asignalling system. A somewhat analogous but different signalling systemis described and claimed in application Serial No. 103,185, of W. E.Berkey, filed September 29,

1936, and assigned to the Westinghouse Electri 8: Manufacturing Company.

I do not wish to be restricted to the specific structural details,arrangement of parts or circuit connections herein set forth, as variousother modifications thereof may be effected without departing from thespirit and scope, of my invention- I desire, therefore,that only suchlimitations shall be imposed as are indicated in the appended claims.

I claim as my invention: 1. In an electric system for controlling theflow of electric energy from a power source to a work circuit.comprising an electric discharge,

device having a control electrode and a plurality of principalelectrodes, a capacitor, means for rect current through an electricdischarge de-,

vice having a pair of principal electrodes and a starting electrode bymeans of apparatus'including a capacitor and means for charging saidcapacitor, said method comprising discharging the capacitor through thestarting electrode and one of the principal electrodes to initiate theflow of direct current through the discharge device, and diverting theflow of direct current from the principal electrodes to charge thecapacitor and to stop the flow of direct current between the principalelectrodes.

3. The method of controlling the flow of di- 8. Apparatus forcontrolling the supply of rect current through an electric dischargedevice having a pair of principal electrodes and a starting electrode bymeans of apparatus including a capacitor and means cooperativelyassociated with the discharge device for charging and discharging thecapacitor, said method comprising charging the said capacitor,connecting the capacitor between the starting electrode and one of theprincipal electrodes to discharge the capacitor and to initiate the flowof direct current between the principal electrodes, disconnecting thecapacitor irom the starting electrode and connecting the capacitorbetween the principal electrodes to divert the flow of direct currentfrom the principal electrodes.

4. In an electric system for controlling the flow of direct current froma power source to a work circuit comprising an electric discharge devicehaving an anode, a cathode, and a starting electrode in contact withsaid cathode, a

capacitor, means for charging said capacitor, means for discharging thecapacitor through the starting electrode and the cathode for initiatingthe flow of direct current through the discharge device, and means,including a portion of said charging means, for connecting the capacitorbetween the anode and the cathode to divert and extinguish the flow ofcurrent therebetween.

5. In an electric system for controlling the flow of direct current froma power source to a work circuit comprising an electric discharge devicehaving a pair of principal electrodes and a starting electrode incontact with one of said principal electrodes, a charge storing means,means for initially charging said charge-storing means, means forconnecting the charge-storing means between the starting electrode andthe principal electrode in contact therewith t'o ini- 40 tiate the flowof direct current through the discharge device, means, including aportion of said charging means, for connecting the charge storing meansbetween the principal electrodes to interrupt the flow of direct currentthrough the discharge device and to charge the charge storchargetherebetween and to charge the capacitor.

7. Apparatus for controlling the supply of power from a direct currentpower source to a direct current power-consumption system compising anelectric discharge device having a pair of principal electrodes and anignition electrode, means for impressing a potential between theprincipal electrodes, a capacitor, 'means for securing an initial chargeon the capacitor, means 0 for discharging the capacitor through theignition electrode and one of the said principal electrodes to initiatea discharge between the principal electrodes, and means for connectingthe capacitor between the principal electrodes to in- 7 terrupt thedischarge therebetween.

power from a direct current power source to a direct currentpower'consumption system com-.[

'prising an electric discharge device having a pair of principalelectrodes and an ignition electrode, means including a capacitor forinitiating a discharge between the principal electrodes, and meansincluding said capacitor for interrupting the discharge between theprincipal electrodes.

9. Apparatus for controlling the supply of power from a'direct currentpower source to a direct current power consumption system com: prisingan electrode discharge device having a pair of principal electrodes andan ignition electrode, a capacitor, a path for charging said capacitorbridging said principal electrodes whereby a discharge between saidprincipal electrodes if it exists is interrupted and a path fordischarging said capacitor including said ignition electrode whereby adischarge'is initiated between said principal electrodes. f

10. Apparatus for controlling the supply of power from a direct currentpower source to a direct current power consumption system comprising anelectric discharge device having a pair of principal electrodes and anignition electrode, means for initiating a discharge between theprincipal electrodes, the said means for initiating a dischargecomprising a capacitor, means for charging said capacitor and means fordischarging the capacitor through the ignition electrode, and means forinterrupting said discharge between the principal electrodes, the saidmeans for interrupting said discharge comprising said capacitor andmeans, including a portion of said charging means. for connecting thesaid capacitor between the principal electrodes.

11. Apparatus for controlling the supply oi power from a direct currentpower source to a direct current power consumption system connprising anelectric discharge device having a pair of principal electrodes and anignition electrode, means for initiating a discharge between theprincipal electrodes, the said means for initiating a dischargeincluding a charge storing means, means for charging said charge storingmeans and means for connecting the said charge storing means between theignition electrode and one of the starting electrodes, and means forinterrupting said discharge between the principal electrodes, said meansfor interrupting said discharge including charge storing means andmeans, in cluding a portion of said charging means, for connecting thesaid charge storing means between the principal electrodes.

12. The method of controlling the iiow of direct current throughanelectric discharge device having a starting electrode and also having apair of principal electrodes connected between a power source and a workcircuit, said current, flow being controlled by means of apparatus iii-Jeluding a capacitor having a. plurality of plates electrically connectedacross the said principal electrodes, said method comprisingdisconnecting at least one plate of the capacitor from one of theprincipal electrodes, connecting the said one plate or the capacitor tothe starting electrode to discharge the capacitor and to initiate theflow of direct current between the principal electrodes, disconnectingthe said one plate of the capacitor from the starting electrode, andconnecting the said one plate 01' the capacitor to the said oneprincipal electrode to direct the flow of direct Qsii Gil

current from the principal electrodes and to charge the capacitor.

13. The method of controlling the flow of direct current through anelectric discharge device having a starting electrode, and also having apair of principal electrodes electrically connected between a powersource and a work circuit, said current flow being controlled by meansof apparatus including a capacitor having a pair of plates electricallyconnected across the said principal electrodes, said method comprisingdisconnecting one plate of the capacitor from one of the principalelectrodes, connecting the said one plate of the capacitor to thestarting electrode, disconnecting the said one plate of the capacitorfrom the starting electrode, and connecting the said one plate of thecapacitor to the said One principal electrode.

capacitor to one of said principal electrodes, and

mean's for connecting the other plate of said capacitor either to theother or said principal electrodes or to the said control electrode.

15. In combination, an electric discharge device having a pair ofprincipal electrodes and a control electrode, means for impressing apotential between said principal electrodes, a capacitor having a, pairof plates, means for connecting one plate-of said capacitor to one ofsaidprincipal electrodes, and means for connecting the other plate ofsaid capacitor at will either to the other of said principal electrodesor to the said control electrode.

16. In an electric system for controlling the fiow of electric energyfrom a power source to a work circuit comprising an electric dischargedevice having a control electrode and a pair of principal electrodes, acapacitor, and means foralternately connectin g'the said capacitorbetween the control electrode and one of the principal electrodes andbetween the pair of principal electrodes.

LEON R. LUDWIG.

